Induction-motor.



PATENTED MAY 26 H, s. MEYER. INDUCTION MOTOR. APPLICATION FILED JAII. 11, 1901.

N0 MODEL.

Fig. 1.

Witnesses Inventor: Hans 5. Meyer,

No. 729,199. 7 Patented May 26, 1903.

UNITED STATES PATENT OFFICE.

HANS STMEYER, OF RUGBY, ENGLAND, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

INDUCTION-MOTOR.

SPECIFICATION forming part of Letters Patent No. 729,199, dated May 26, 1903.

Application filed January 11, 1901. Serial No. 42,829. (No model.)

To aZZ whom it may conc rn: means of which the potential at the motor- Be it known that I, HANS S. MEYER, a subterminals is regulated'in accordance with the ject of the Emperor of Germany, residing at. load on the motor. This regulating device is Rugby, England, have invented certain new a transformer, and, as shown, it comprises 5 and useful Improvements in Induction-Mothree compensator-windings d, e, andf, contors, of which the following is a specification. nected at one end to the common conductor My invention relates to alternating-current 4 and having their other terminals connected, motors of the induction type, and has for its through the conductors 1, 2, and 3, to the object to reduce to a minimum the wattless lower terminals of the switch S. Each of I0 current required by such motors. the compensator-windings is provided with In many installations where induction-moa plurality of terminals arranged in the arc tors are employed it is required that the moof a circle, so that. they may be engaged tors shall have a large starting-torque. If, by contacts carried by the arms of a conhowever, the motors are constructed to give tact-lever O, pivoted at 0. The contacts 15 a high torque at starting, they will take a carried by the arms of the said lever are suitlarge magnetizing-current, and willtherefere ably connected to the conductors 5, 6, and load the mains with an unnecessarily large 7, leading to the terminals of the motor M. wattless current when running under normal The contact-lever is normally maintained in load as well as when running light. the position shown in the drawings by means 70.

20 It is the purpose of my invention to do of a spring m and is moved fromthis position away with excessive magnetizing current in accordance with the load on the motorwithout reducing the starting-torque and the circuit-by means of a solenoid It, included in overload capacity of the motor, and since the circuit with one of the conductors leading to starting-torque, as well as the output of an the motor, the core t' of the solenoid being 25 induction-motor, is proportional to the secattached to one of the arms of the contactond power of the potential at the motor-terlever. In order to prevent the contact-lever minals, while the magnetizing-current is difrom being moved to unduly increase the porectly proportional to the potential,I am entential at the motor-terminals at the moment abled to accomplish the desired result by proof starting due to the momentary rush of cur- 8o 3o viding the motor with a regulating device rent in the motor-circuits,adash-potnis prowhich operates automatically to adjust the vided, having its piston 20 connected to one potential at the motor-terminalsin suchamanof the arms of the contact-lever. The cylinner as to cause it to increase with an increase den of the dash-pot is provided with two of the load on the motor and to decrease with openings, one, 19, at the bottom and another 35 a decrease of the load. larger opening, 4), at the side and just above My invention will be understood by referthe piston when it is in its lowest. position. ence to thefollowingspecificationwhen taken If the motor is started without load, then, in connection with the accompanying drawsince the rush of current will exist only moings, while its scope will be pointed out in the mentarily, the solenoid It will be unable to o appended claims. change the position of the contact-lever suffi- In the drawings, Figure 1 represents diaciently to move. the piston of the dash-pot grammatically one arrangement of a regulatbeyond the opening 'u before the motor has ing device by means of which my invention reached a sufficient speed to reduce the curmay be carried out, and Fig. 2 illustrates a rent tosubstantiallyits normal no-load value;

4; modified arrangement. but by the time that the motor has reached In Fig. 1, Mindicates a three-phase inducits full speed the piston of the dash-pot will tion-motor, and A, B, and O the mains of a have been raised above the opening 1) and three-phase supply system. S is a switch inthereafter the dash-pot will oifer no appreciterposed between the supply-mains and the able resistance to the movement of the 'con- Ico 5 conductors through Which current is supplied tact-lever. When, therefore, aload is thrown to the motor. R is the regulating device, by onto the motor after it has been started in operation or whenever the load on the motor is increased, the contact-lever will be immediately moved under the influence of the solenoid to increase the potential to an amount suflicient to supply the motor with the magnetizing-cur'rent requisite for that load. By properly adjusting the device the magnetizing-current may be caused to have the smallest possible value consistent with the load on the motor. If it is attempted to start the motor under a load so great that it is unable to start at the low potential whichis initially supplied to the motor-circuits, a large current will continue to flow in the motor-circuits, and therefore through the solenoid 70, until the piston in the dash-pot is drawn above the opening c, When the voltage will be immediately adjusted to the amount necessary to start the motor. The nearer the speed of the motor approaches to synchronism the less will be the value of the current taken from the mains, and as the current in the mains falls off the spring m will overcome the pull of the solenoid 7r upon its core 2', and thereby the potential at the motorterminals and at the sametime the magnetizing-current taken by the motor will be reduced.

The arrangement shown may be modified in various ways. For example, the solenoid k may be connected in any one of the circuits 5 6 7, or it may be connected in one of the circuits 1 2 3 between the source and the compensators, or instead of being included directly in circuit with one of the mains it may be placed in shunt to a portion of the same. Also in place of the transformer any other suitable regulating device may be used.

In Fig. 2 I have shown a modified arrangement for preventing a too rapid operation of the potential-controlling device. In the arrangement shown in this figure the contactlever is operated by a separate motor M, the connection between the motor-shaft and the lever being indicated by dotted lines as a belt connection, although evidently the connection may be made in any desired manner. The motor M is connected to the supply-circuit through three contacts mounted on a switch-arm r and arranged to engage with one or the other of two sets of contacts g and h, reversely connected to the supply-mains. The switch-lever r is normally drawn toward theset of contactsg by the spring-m; butwhenever current is flowing in the motor-circuit the solenoid 7c, connected'in circuit with the conductor 1, will be energized to draw in its core 1' and to move the contacts on the switchlever r toward the set of contacts h,connected to the conductors 11, 12, and 13. With the parts in the position shown in the drawings as soon as the switch S is closed current will flow through the conductors 1, 2, and 3 to the compensator-windings and thence by way of conductors 5, 6, and 7 to the motor-windings. If the current required by the motor is more than normal, the solenoid it will actuate the switch-lever r and will bring the contacts carried thereby into engagement with the set of contacts h, supplying current to the motor M in such a direction as to cause it to move the contacts on the lever O to increase the potential at the motor-terminals. When the current falls to its normal value, the switchlever rwill be maintained in the mid-position, (shown in the drawings,) and when the current falls below normal the lever is drawn by the spring m into such a position that the contacts carried thereby are caused to engage the'set of contacts 9. Current is then supplied to the motor M in a reverse direction, and the contact-lever O is moved in a direction to reduce the motor-potential. In order that the circuit of the motor M maybe opened whenever the contact-lever O has been moved to either of its extreme positions, a lost-motion device of any suitable mechanical construction is interposed between the contact-lever O and the switch-lever r. In the drawings I have indicated this device as comprising an arm t, loosely mounted on the same pivot with the contact-lever and connected by a rod 8 with the lever r. The contact-lever is also provided with two lugs a and b, one of which is brought into engagement with the arm 25 in each of the extreme positions of the said lever. By means of this device the lever r is forced into its mid-position whenever the contact-lever is in either of its extreme positions; The spring 'm is so proportioned with respect to the pull of the solenoid is that current is supplied to the motor M through the set of contacts 9 as long as the current supplied to the motor M remains below normal. When the normal current-flow is reached, the lever r is drawn into its midposition and when the current rises above normal the circuit to the motor M is closed through the set of contacts h. This arrangement operates as follows: Whenever the main motor M is cut-out of circuit, the contact-arm will always stand on the point of the lowest potential and the contacts on the switch-arm r will be drawn toward the contacts g, connected to the conductors 8, 9, and 10. As soon as the main switch S is closed the contacts of the switch-lever 1 will be drawn into engagement with contacts h, which constitute the terminals of the conductors ll, 12, and 13, and the motor M will be supplied with current in such a direction as to move the contact-lever right-handedly to increase the potential on the motor-terminals. As soon as the contact lever has reached the point of highest potential the circuit is automatically broken at the switchlever r by means of the lost-motion device and the motor M is stopped. It now the main motor M continues to increase in speed, the current will decrease in the mains (at normal load below the normal value, since the potential at the motor-terminals is above normal) and the spring on will move the switch-lever 4 into such a position as to supply current to the motor M in the opposite direction and the contact-lever will bemoved in left-handed rotation until the current in the motor-circuits has been increased to the normal value, when the contact-lever will be brought to its mid-position, thereby opening the circuit of the motor h Whenever the load varies, the strength of the current changes in the solenoid 7t, and therefore the switch-lever r is constantly vibrating back and forth, so as to close the circuit of the motor M first in one direction and then in the other, and thereby whenever the load varies from normal the potential at the motor-terminals is immediately increased or decreased, as the case may be.

\Vhat I claim as new, and desire to secure by Letters Patent of the United States, is

1. In combination, an induction-motor, and automatic means constructed and arranged to vary the potential at the motor-terminals in such a manner as to cause it to increase with an increase of the load on the motor and to decrease with a decrease of the said load.

2. In combination, an induction-motor, a source of variable potential therefor, and automatic means for varying the potential of said source in such a manner as to cause it to increase with an increase of the load on the motor and to decrease with a decrease of the said load.

3. In combination, an induction-motor, a source of variable potential therefor, means for varying the potential of the source in accordance with the load on the motor, and a retarding device for preventing a sudden increase of potential due to the rush of current at starting.

4. In combination, an induction-motor, a source of variable potential therefor, means for varying the potential of the source in accordance with the load on the motor, and a retarding device constructed and arranged to prevent a sudden increase of potential due to the rush of current at starting but permitting a quick change of potential upon change of load.

5. 'In combination, an induction-motor, a source of current-supply therefor provided with a plurality of terminals of varying potentials, contacts connected to the motor-circuits and arranged to engage said terminals, means tending to maintain said contacts in the position of lowest potential, a motive device controlled in its operation by current flowing in the motor-circuits for actuating said contacts, and a retarding device comprising a dash-pot provided with an auxiliary opening arranged to permit a free movement of the contacts under the influence of the motive device after the motor has been started in operation.

V In witness whereof I have hereunto set my hand this 24th day of December, 1900.

HANS S. MEYER.

iVitnesses:

LEONORE RASCH, BENJAMIN B. HULL. 

